If you are going to run it on 120V, there is two choices for good welders, the
Lincoln or the
Miller.
If you need more juice for thicker stuff, than you can go to the similar 220V models from the same manufacturers, they will be pricier though.
LincolnMillerI bought the Lincoln from this eBay vendor (because it was a little bit less expensive), I think it's the best deal around and the service was excellent, so I can recommend them.
Take your time and see what you actually will do with the welder before commiting.
Don't forget also about the gas bottle, decide if you want to rent one or buy your own and have it filled. If both of you are going to do work, then go for a bigger bottle anyway.
There are less expensive units out there, but parts availability and quality of manufacturing and versatility will not be as good. If you're on a budget try going for a good quality used machine. You may be lucky but from what I saw, the ones on eBay go for a pretty penny and I preferred to put the extra $100 and just buy a new one.
Good luck!